WASHINGTON — The first to fall in the Korean War are also among the first casualties of the current diplomatic impasse between the United States and North Korea.

Almost 60 years after the end of that conflict, American officials had hoped that thawing relations with North Korea would allow a team of forensic and archeological experts to visit that country to search for the remains of thousands of U.S. servicemen who are thought to have died there but whose bodies were never recovered.

The latest flare-up over the North Korean nuclear weapons program has dashed those hopes.

Just a month ago, in late February, it looked as if the remains-recovery effort would be possible, almost likely. North Korea stated a willingness to suspend long-range missile testing. An American team assembled in Hawaii and prepared to head to North Korea, perhaps in April. It would have been the first time since 2005 that Americans had been allowed to search for an estimated 5,300 U.S. war dead still there.

"The sites that were identified for these excavations are areas where hundreds of American servicemen were lost in battle," the Pentagon said. Experts note that they fell in battlefields that have long since been returned to farming or abandoned.

But by mid-March, North Korea announced intentions of a three-stage missile launch. The North Koreans insist the launch, planned for mid-April, is to put a satellite into space and to honor founder Kim Il Sung's 100th birthday (he died in 1994). A North Korean Foreign Ministry statement on the matter noted: "We will never give up the launch of a satellite for peaceful purposes" and urged President Barack Obama to "acknowledge that we also have a right to launch satellites."

But, U.S. officials note, the planned launch, only weeks after a promise to suspend such launches, is an unacceptable breach of trust. The fear is that a launch, even for peaceful purposes, advances the North Korean weapons program.

"This is a matter of North Korea meeting its obligations," said Navy Capt. John Kirby, a spokesman for the Defense Department. "At this time, they've shown no willingness to do that. We can't reward such behavior."

Cooperative efforts were put on hold. Over the weekend, Obama noted that food aid could be withheld if the launch goes ahead. It also meant remains-recovery efforts, once again, were locked out.

While the remains in question are American, as are the families waiting for news, Defense Department spokesman George Little noted that North Korea benefits from the recovery efforts as well.

"They build goodwill in the eyes of the world by showing cooperation," he said. "They also lose by this suspension."

Cmdr. Leslie Hull-Ryde, a military spokesperson on this issue, said the search for fallen troops in North Korea remains a high priority. The missing represent the highest number from any conflict. In fact, the last American remains from Iraq were recently brought stateside.

The high number of dead still in North Korea is the result of both a bloody conflict and a nightmarish diplomatic situation.

In fact, in the 59 years since the end of the Korean War, American investigators have only been allowed inside North Korea to search for war dead between 1996 and 2005. During that time they found the remains of a suspected 229 troops, though only a few have been identified.

At other times, North Korean officials have turned over boxes of remains — 200 such boxes between 1990 and 1994, and another six in 2007.

U.S. success in identifying remains, however, has been slow. In all, 92 individuals have been identified.

As for when the recovery efforts might again be scheduled, Little noted, "That's entirely up to the North Koreans."